Children in the poorest regions still have worse teeth than the rest of the country - and there are warnings that more has to be done if real gains are to be made.

Nationally, 40 percent of five-year-olds who got dental check-ups last year had some form of tooth decay, according to the latest figures from the Ministry of Health.

But in regions like Northland and Tairāwhiti, that figure is much higher.

Tairāwhiti District Health Board covers Gisborne and the East Coast, and about half of all five-year-olds there have some form of tooth decay.

Dental service manager Arish Naresh said while all young children were enrolled with the DHB's oral health service, that didn't necessarily translate to families actually showing up for appointments.

"Here in Gisborne a lot of people work in forestry or out in the field, so they leave their homes at 5am, get home at 6pm, it doesn't make any sense for us to pencil in an appointment at 1pm for the child, they will not take time off, especially when they are [low] paid workers."

To get around that, Mr Naresh said they started running clinics in the evenings and at the weekends.

"And actually our numbers of missed appointments is really low in our evening and weekend clinics, compared to our normal clinic days."

While the statistics around the prevalence of tooth decay aren't budging, there are improvements in the number of children needing a general anaesthetic to have teeth removed.

Last year it was 138 and this year it was 83, Mr Naresh said.

Mr Naresh said he hoped to see a bigger turnaround in the statistics in about three years' time.

But the region with the worst teeth was Northland.

Almost 56 percent of five-year-olds there have some form of tooth decay.

Northland DHB oral health adviser Neil Croucher said while the statistics were not getting any better - they at least weren't getting any worse.

"The only good piece of news around that is we are seeing the severity of decay improve, but not what we call the prevalence of decay. There are still the same number of five-year-olds with one or more decayed teeth, and obviously we're slightly disappointed with that."

It was important that children get in as early as possible for a check-up.

"From the moment the first tooth comes through, we are really keen to meet you, we are really keen to meet the parents, and therefore we can then have a discussion around how to look after teeth and how to keep teeth healthy."

One thing that could make a big difference to Northland's dire statistics would be adding fluoride to the region's water.

About half of the population is connected to town water supplies, Dr Croucher said.

In areas where water couldn't be fluoridated, Dr Croucher said they offered what was called a fluoride varnish, which helped strengthen and protect children's teeth.

Otago University dental public health expert Jonathan Broadbent said improving oral health was not just about what happens in the dental chair.

He wants more done to get basic oral hygiene messages out there, like brushing twice a day with fluoride toothpaste - and making sure people have access to those products.

"Initiatives, like maybe even taking the GST off these products and providing some degree of subsidy, even if it's just for children's oral health self-care products, so that people know that it's a priority and they can see that it's more accessible and more affordable to them," he said.

Dental Association president Bill O'Connor blamed an under-resourced publicly funded oral health service for the level of decay.

He said DHBs struggled to attract and retain staff, and that had flow-on effects.

"Last year over 100,000 kids didn't get their check-up - that's a lot of kids sitting there who are missing out on getting checks, so those cavities are not getting picked up when they're small and easy to treat, that's why we ended up with last year 36,000 children having one or more teeth extracted."

Mr O'Connor said therapists were doing a good job, but there have to be more of them.

Unless more work was done to understand why so many children had such serious problems with their teeth, Mr O'Connor said the statistics were unlikely to budge.